There are currently available a number of beverages, and concentrated beverage compositions (including liquid, powdered or tablet concentrates) to be prepared by the consumer into a drinkable form, which are used for rehydration of fluids lost during exercise or vigorous activity. These rehydration beverages (also known as “sports drinks”), both in the ready-to-drink form and as prepared by the user, may be consumed before, during and after exercise. While these sports drinks rehydrate the body better than plain water, there remains a need for a superior rehydration beverage that addresses many aspects of rehydration such as voluntary fluid consumption and fluid retention.
Rehydration can be accomplished in a number of different ways. In the most basic sense, water replaces some of the fluids lost through sweat and helps maintain body temperature and important cardiovascular functions. Sports drinks have been developed which replace the fluids and electrolytes lost through sweat. This is an improvement over plain water not only because these drinks replace some of the minerals lost in sweat but also because carbohydrates are provided as a source of added energy. However, rehydration would be improved if the beverage also improved fluid retention, reduced urinary fluid loss, stimulated increased voluntary consumption, possessed superior sensory qualities, and supported the physiological response to continue drinking.
Conventional sports drinks typically contain water, small amounts of minerals/electrolytes and an energy source in the form of carbohydrate compounds. The scientific rationale for inclusion of common electrolytes such as sodium and potassium rested on the intuitive notion that it would be logical to replace some of the electrolytes lost in sweat. Stimulating voluntary fluid intake and promoting fluid retention were either secondary considerations or worse, not considered at all.
In addition, the mineral content of sports drinks varies widely. For instance some beverages can contain 5 mEq/L of sodium while others can contain over four times that amount. Similarly, there are wide differences in the content and amounts of other minerals, such as potassium, magnesium and chloride.
Some research has indicated that sodium content in fluid replacement beverages has a marked effect on fluid retention after exercise. Basically this research shows that when subjects ingest standard volumes of solutions containing sodium in the range of 40-100 milliequivalents per liter (mEq/L), rehydration is improved by increasing fluid retention and maintaining positive fluid balance. However, the palatability of a fluid replacement beverage containing an increased amount of sodium was not considered. Nadel E., Mack G., and Takamata, A., Thermoregulation, Exercise, and Thirst: Interrelationships in Humans. In Perspectives in Exercise Science and Sports Medicine: Exercise, Heat, and Thermoregulation, vol. 6, pp. 225-251, (Gisolfi, Lamb and Nadel eds., Indianapolis Ind., Brown and Benchmark, 1993); Maughan, R. J. and J. B. Leiper, Sodium Intake and Post-Exercise Rehydration in Man, Eur. J. Appl. Physiol. 71:311-319, (1995); Shirreffs, S. M. and R. J. Maughan, Volume Repletion after Exercise Induced Volume Depletion in Humans: Replacement of Water and Sodium Losses, Am. J. Physiol. 43:F868-F875, (1998). These articles are hereby incorporated by reference.
Fluid replacement after significant dehydration is driven by various physiological changes. The two major physiological drivers that encourage voluntary drinking are plasma osmolality and plasma volume. During exercise, the loss of fluid through sweat causes plasma volume to drop and plasma osmolality to increase. These physiological changes cause a thirst response which drives voluntary fluid consumption. Scientific studies have shown that sodium also plays an important role in regulating plasma volume and osmolality. Ingesting beverages containing sodium helps increase the rate at which plasma volume and osmolality return to normal. However, ingesting too high a level of sodium causes rapid restoration of plasma volume, which reduces the drinking response and prevents adequate rehydration. In addition, the sensory properties of a beverage containing too high a level of sodium are unfavorable, and would further reduce the drive to drink. Wemple, Richard D., Morocco, Tamara S., Mack, Gary W., Influence of Sodium Replacement on Fluid Ingestion Following Exercised-Induced Dehydration, Int'l J. Sport Nutrition & Exerc. Metabolism 7:104-116 (1997). This article is hereby incorporated by reference.
It is further believed that other electrolytes and minerals play an important role in rehydration by possibly affecting fluid replacement and fluid retention. In response to fluid loss during dehydration, water is distributed between fluid compartments so that both the extracellular and intracellular compartments share the water deficit. Sodium, potassium, magnesium, calcium and chloride are some of the more important electrolytes/minerals involved in filling these body fluid compartments, particularly sodium, chloride, potassium and magnesium. Beverages providing sodium and chloride encourage the filling of the extracellular compartment, while beverages providing potassium, magnesium, and calcium favor the filling of the intracellular compartment. Properly balancing the sodium, potassium, magnesium, calcium and chloride levels will further improve the rehydration properties of the beverage.
These electrolyte ions assist in filling these body fluid compartments more rapidly and help to retain the fluid instead of it being excreted as urine. Since both sodium and chloride ions favor the filling of the extracellular compartments, substitution of one with the other may not affect the overall result. The same may be true for potassium and magnesium in regards to intracellular hydration.
U.S. Pat. No. 4,981,687, issued to Fregly et al., incorporated herein, discloses a beverage comprising water, sugar, and electrolytes, an improvement wherein said beverage further comprises glycerol, pyruvate and/or caffeine. The sugar contained in the beverage claimed in this patent can be glucose, sucrose or other appropriate sugar compound, with glucose at a concentration of from about 2% to about 8% being specifically disclosed and glucose at a concentration of about 4% being preferred. Examples of electrolytes disclosed in this patent include 15-30 mEq/L sodium, 1-5 mEq/L potassium, 2-8 mEq/L phosphate, bicarbonate, sulfate, chloride, calcium, and magnesium.
The beverages as disclosed above are said to ameliorate the adverse physiological effects which can result from physical exertion and heat exposure. The present invention also seeks to address the adverse physiological effects of physical exertion, but without including stimulants or other chemical compounds which may have known acute effects (e.g. glycerol and pyruvate promoting gastrointestinal distress) and unknown long-term effects.
Therefore, a need exists for a rehydration beverage that supplies necessary electrolytes and energy sources, exhibits organoleptic properties which are substantially equivalent or superior to those of typical sports drinks, and provides superior rehydration by addressing several mechanisms affecting rehydration, such as fluid retention and voluntary fluid consumption. Furthermore, a need exists for a method that ameliorates the effects of dehydration, enhances rehydration, and addresses mechanisms such as fluid retention, and urinary loss.
The present invention fulfills these needs. The beverages of the present invention enhance rehydration, supply necessary electrolytes and energy sources, exhibit organoleptic properties at least substantially equivalent to other sports drinks, improve fluid retention and voluntary fluid consumption. The method of the present invention also addresses the above concerns through the administration of the composition of the present invention. The composition may be administered orally. And the composition can take many forms including but not limited to, liquid, gel, dry powder, tablet or capsule. Concentrated forms of the composition such as a powder can be can be added to water and/or other liquids which can include electrolytes and/or carbohydrates, including even sports drinks such as Gatorade® in order to provide beverages of the present invention.
Dehydration is reduced and fluid retention is improved by abating urinary loss when one embodiment of the present invention is taken during exercise, as illustrated in Example 2 hereof. Examples 3 through 7, further show that the present invention reduces the effects of dehydration, improves fluid retention, reduces urinary fluid loss, and possess superior sensory properties which should improve voluntary fluid consumption when taken after activity-induced fluid loss. It is further believed that similar results should be obtained when the beverage of the present invention is taken before activity-induced fluid loss.